Bacch Dsp, True stereo?

By the way there is no "true" stereo...😁

This true stereo concept had no meaning in acoustic save if we use this expression to characterise many speakers system of home theater compared to it...

There is acoustic day to day TRUE experience of sound and music , and there is recording always defective or imperfect reproduction through  headphone or 2 speakers or many speakers for specific reasons in each case  in acoustic.. Dr. Choueiri explain it way better than me...

To start the understanding read this article it is simple to read :

«In 2014, Choueiri founded Theoretica Applied Physics to manufacture and market audiophile-caliber components incorporating his patented innovations.

There’s a problem, Choueiri and many others maintain, with the way that stereo recordings have been played back for the last 70 years or so. “If you go out in the forest and you hear a bird singing, it’s not because there are two birds singing,” Choueiri explained with his characteristic intensity. “There’s one bird singing.” Stereo only creates the illusion of localized sound by manufacturing a phantom image “and your brain doesn’t believe it.” In life, a sound is precisely localized because of a slight difference in the arrival time at the right and left ears, as well as slight differences in amplitude and tonality that are attributable to the physical presence of the listener’s head and the shape of his or her ears. With reproduced sounds emanating from two loudspeakers, these relationships are considerably degraded, especially if the listening environment introduces reflections. Each ear isn’t hearing what it’s supposed to—inter-aural crosstalk is spoiling the party.»

https://www.theabsolutesound.com/articles/theoretica-applied-physics-bacch-sp-adio-stereo-purifier/

It's not a new fad. Ralph Glasgal has been promoting DSP crosstalk reduction for a long time. Polk, Carver, Lexicon and others have tried to tackle the crosstalk problem over the years using analog methods. It's a real problem, a real shortcoming of 2 speaker stereo reproduction. It's not intentional or desirable in any way, although some may develop a taste for it. 2 speakers is the simplest stereo possible and it beats mono, so that's why it became a standard. It has nothing to do with any inherent audio superiority, although with crosstalk reduction it can get so good on properly made recordings that it's harder to argue the need for multi-channel formats. Still, I think well done up-mixing of stereo recordings to 5 or 7 speakers located across the front of the listening area has some great upside potential, especially for creating a huge sweet spot. Purpose made recordings for this kind of setup would even be better, but that's not likely to happen.

Adding crosstalk to headphones may make some sense, but ideally you would not want to do it with the same time delay that happens across your head with stereo speakers. If you do so, you'll introduce massive comb filtering to the signal for center panned sounds, just like speakers do to your ears. Now that I say that, I can think of a way to add time delay without causing comb filtering to center panned sounds - I think I'll have to try that!

I've not tried the BACCH DSP yet, but I'll vouch for crosstalk reduction. From the reviews I've read of BACCH it sounds similar to my own experiences with using a physical divider or my own, not so powerful channel mixing methods. The timbre of center panned sounds is very nicely improved, as is the overall sense of acoustic space. It matters more on some recordings than others. I never heard anything that sounded worse because of it, although I'm just reducing crosstalk, not creating the extreme degree of left right separation that BACCH DSP can. 

I think it cost like $30,000 to do this.

And the complexities of all the computer interfacing.

They have several levels.  I think you can do the base level for under $2k. 

Wait a second, has anyone in the Audiogon forums actually heard BACCH, or is this just repeating things said on the Internet? Not being snarky, I'm serious.